Blueberry filling /Berry fillings for pie

Blueberries are not a common sight in Mumbai. We have to eat these mostly in form of jam or preserve. A friend said that we get these at some places (crawford market, hypercity etc.) during fag end of monsoons. But the quality is not always up to the mark. I mean they never taste ripe and juicy, they are either tart or too powdery.
Well, I am yet to taste the fresh batch in mumbai, but in the mean time, have found a place that stocks the frozen berry's. These were stored in some thick syrupy water. 
It could have been just sugar syrup or maybe corn syrup, dont know. But if you are lucky to find fresh berries, then simply follow the recipe below to get your nicest filling ready.
Else, like me if you are working with frozen then simply reduce the sugar to 50% below and check for the corn starch as well.

Ingredients

2 cups of frozen / fresh blueberries

1/2 cup water

1/2 cup of sugar

1 tspn of lemon juice

2 tbsp corn starch

Method

1) In a heavy saucepan, mix the berries, sugar and lemon juice and let it cook until the mixture starts boiling.

2)Mix the water and corn starch together. Add this to the blueberry mixture in a steady stream.

3) Stir constantly until it reaches the desired consistency. 

4) Store it in a nice jar. 

Keeps well in  refrigerator for about 2-3 weeks.

You can also use this recipe for other berries.